The 1999 Mallory & Irvine Research Expedition was mounted to highlight mountaineering's greatest mystery: Were Mallory and Irvine the first to reach the summit of the world's highest mountain? A team of professional mountaineers, guides, and climbing Sherpas, supported by top researchers and historians and backed by media and outdoor industry sponsors went to Mt. Everest to find the answer. Against extremely long odds, their results made mountaineering history.

Expedition leader Eric Simonson was joined by professional climbers Conrad Anker, Dave Hahn, Jake Norton, Andy Politz and Tap Richards. Research historians Jochen Hemmleb and Larry Johnson supported the effort with detailed search strategies. BBC and PBS Nova film crews were on location to document the team's activities. They arrived at Base Camp in March 1999 to find Everest with extremely thin snow cover after a relatively dry winter. The conditions for a search were optimal.

On May 1, 1999 the first team ascended from Camp 5 into the search zone for an initial attempt to locate clues to solve the mystery. Within several hours, the remains of George Mallory were spotted by Conrad Anker. The team assembled there and after documenting the site, undertook hours of high altitude excavation through the frozen terrain in order to gain access to Mallory's pockets. After recovering items of significance, the team labored to gather loose stones and performed a burial and committal ceremony before darkness began to fall.

The condition of Mallory's well-preserved remains indicated a fall of only moderate distance, but severe enough to inflict a broken leg and a serious head injury. A length of climbing rope, still tied around his waist, had caused significant bruising around his torso. The collection of items recovered included an altimeter, climbing goggles, personal notes and letters, detailed inventory lists of provisions at various camps, monogrammed handkerchiefs and clothing labels, a wrist watch, matches, a pocket knife and a small tin of food. Notably not found at the site were any signs of Irvine, any oxygen apparatus and a photo of Mallory's wife, which some believe he carried for placement on the summit.

During a later effort high on the North Ridge, climber Tap Richards recovered an oxygen cylinder that Simonson had spotted years before. This was definitively shown to be from the 1924 expedition and was likely discarded by Mallory and Irvine during their climb. After completion of the expedition the team returned to the US, where Hemmleb performed an extensive study of the items recovered. Based on this analysis several hypotheses about the events of Mallory and Irvine's summit day were developed. The team's collaboration on an official account of the expedition and its findings entitled Ghosts of Everest was published by The Mountaineers Books in the fall of 1999.